Computer Science XI

Unit 1: Introduction and Evolution of Computer System

Introduction to Computer System
Computer is derived from the Latin Word ‘Computare’ which means to calculate
A computer is defined as the programmable electronics device that takes data and instructions, processes them and gives the information as required. Moreover, it also stores huge amount of data

Characteristics of a Computer
Speed: Processing capacity of a computer with respect to time and it measures in terms of Hz or MIPS
Accuracy: Computer is considered as 100% correct but if there is wrong input, the output must be wrong, also called GIGO (Garbage In Garbage Out)
Automatic: Computer can do the operations automatically guided by the instructions from the users
Reliability: Because of the accuracy with speed, we must dependent on computer
Storage: Computer can store huge amount data with high security
Diligence: Capable of doing the same job repeatedly with equal efficiency
Versatility: Performs different types of jobs
Non Intelligent: Computer can do nothing without giving instructions, depends on users. Moreover it has no intelligence power
Word length: The number of bits which can process at a time by a CPU.

What computer can do?(Capability)
Performs computation far faster than human with 100% correct
Stores huge amount data safely
Can do the same job without getting bored
Provides the information for decision making
Provides faster and Cheaper Communication
Performs wide Varity of jobs: Research, Engineering, Medical, Space, Business etc 

What computer can not do?(Limitations)
Does not know the right and wrong input so called idiot servant
Does not have intelligence power, guided by the program and the devices made by the human being
If there is error in the computer, it does not fix the error itself

Advantages of Computer
Computer is 100% accurate machine so most of the people rely on it
Computer is far faster than human beings
(3.2 GHz=3.2X109 instructions per second)
Computer can do wide variety of jobs at the same time
Computer can store large amount of data safely
Computer has many applications in day today life

Disadvantages of Computer
Computer is difficult to afford by the poor people
Computer totally depends on electricity and there might be risk of electric shock
Hardware and software failure causes the data lost.
Most of the people are dependent on machine, therefore people become lazy

Major Components of Personal Computers (PCs) :
1.Input Devices
Examples: Keyboard, Mouse, Microphone, Scanner, Webcam, etc
2.Output Devices
Examples: Monitor, Speaker, Printer, Projector, Plotter
3.Main Board (Mother Board)
4.Processor (CPU)
5.Memory (RAM, ROM)
6.Hard Drive (Hard Disk)
7. Floppy Drive
8. Ports and Expansion Slots
9.CD or DVD Drive
10. Power Supply

Major Components of PC
Program
A finite set of instructions to the computer to perform some specific task or job. Example: Notepad, Searching Program, Program to calculate Simple Interest
Hardware
Electronic or electro-mechanical components of computers which we can feel or touch are called hardware. Example: keyboard, mouse, monitor, etc.
Software
A set of programs, data or files which execute inside computer is called software. Example: MS Word, MS Windows, Adobe Photoshop, etc.
Firmware
A set of microinstructions which are fabricated inside a chip is called firmware. Example: Booting Program of ROM Chip, BIOS(Basic Input Output System), etc.

How Does Computer Work?
Step 1: Takes data and instructions from the input devices such as keyboard or mouse
Step 2: Processes data as per the instructions given by the user
Step 3: Stores processed data i.e. information in storage unit which comes from processing unit
Step 4: Provides information to the end users using output devices such as monitor, speaker or printers

Applications of Computer
1.Banking
Banks use computers for transaction processing, keeping accounting and financial data, maintaining payroll system, keeping customers’ records, controlling ATM (Automatic Teller Machine) and also use for decision making for the manager.
2.Offices
It is used for daily activities like data processing, text editing, data calculations, office automation, etc.
3.Reservation System
Airplanes and railways offices use computer network for the online reservation. It is more cost effective and efficient method.
4. Education
Computer is very useful learning and teaching aid. We can demonstrate problems with audio video and animations. Different online education, online library, tutorials etc are very popular these days. 

5.Health and Medical fields
Computers are used in hospitals for recording patients’, doctors’ and employees’ information. For the diagnosis of the diseases, medical research, and decision making form the experts system by the doctors.
6. Weather Forecasting
Computers use the pictures of the clouds and the weather information from the satellite and analysis these information for weather forecasting.
7.Science and Engineering
It is used in the field of General science, biological researches, nuclear physics, environmental science etc. Also used in different computer engineering works:
CAD (Computer Aided Designing)
CAM (Computer Aided Manufacturing)
CASE (Computer Aided Software Engineering)

8.Graphics and Animation
Graphics is mostly used in print media, internet, magazines, books, advertisements, photography, etc.
Animation is the process of adding effects on objects with the help of computer software. Mostly used in film industry, TV and websites.
9.Simulation
It is used to predict the real world situations with help of computer system. It is very effective method for the scientific and risky experiments: like nuclear simulation, rocket simulation, flight simulation, etc
10.Military and Weapons
Developed Countries use smart weapons which are controlled by the computers. Modern tanks, mine disposable weapons, missile, etc are guided by the computerized system. Moreover it is also used for keeping security information, communications, etc.
11.Library
Now a days, books are digitized and stored in computer. It makes easier for the readers to search books and to select particular topic as required.

12.Research and University
Researchers have to work on complex calculations and data analysis in university. So such kind of jobs are easily be carried out by using different kinds of computer aided tools and software.
13. Communication
Computers are used in telecommunications, networks, internet. Text, graphics, voice, video data can be transmitted from one place to other with the help of computer and communication channel.
14. Business
Business house such as shops, malls, supermarkets, retailers, etc use computer for file management, business data processing, data analysis, billing, administrative works, records keeping and decision making.
15. Desktop Publishing
Pre-press activities such as formatting, designing of pages, news paper, magazine, books etc. Such activities make the layout of the document attractive and informative.

Evolution of Computer
History of Computers is divided into three eras:
Age of mechanical calculators (Early-1900s)
Age of electromechanical computers (1900-1960)
Age of electronics computers (1960-Till)

Age of Mechanical Calculators
Abacus
Intheearlydays,peopleusedpebbles,beads,onacountingboardtocarryoutsimplecalculationcalledAbacus.ItwasthefirstmechanicalcountingdevicecreatedbytheChineseorEgyptianduring600B.C.
NapierBone
ScottishMathematicianJohnNapierdevelopedlogarithmictablein1614.Onthebasisofthistable,heinventedsmallinstrumentcalledNapierBoneRodin1617A.D.tocarryoutsimplemultiplication.

SlideRule
BasedonJohnNapierPrinciples,anEnglishMathematicianWilliamOughterddevelopedarulerlikeinstrumentcalledSlideRulein1620A.D.Itcouldperformaddition,subtraction,multiplicationanddivision
Pascal'sCalculator
FrenchMathematicianBlaséPascaldevelopedthefirstmechanicalcalculatorin1642A.D.Ithadsomecogsandgearforthecalculation,Itcouldperformaddition,subtractionupto8digits.SohisworkwashonoredbyNiklausWrithbygivingtheprogramminglanguagenameasPascal.

SteppedReckoner
GermanMathematicianBaronGottfriedVonLeibnizmodifiedPascal’smachineandinventednewmachinein1671calledSteppedReckoner.Itcouldperform,addition,subtraction,multiplication,divisionandevensquareroot.
Jacquard’sLoomandPunchCards
In1802,TextileManufacturerJosephMarieJacquarddevelopedautomatedclothweavingmachinecalledLoom.Itwasbasedontheprincipalofpresenceandabsenceofsomeholes.Afterthat,healsodevelopedapunchedcardonthesameprinciple.

DifferenceEngine
In1822A.D.,EnglishMathematicianCharlesBabbagedevelopedDifferenceEngineatCambridgeUniversity,Itwasusedforsolvingcomplexmathematicalequations.
AnalyticalEngine
In1833AD.,hedevelopedanothermachinecalledAnalyticalEnginewhichwasthesignificantimprovementinthehistoryofcomputer.Itwasbasedontheinput-process-output.Ithadthreeunits,millasprocessingunit,punchedcardswereusedasdatainput/outputandstore.Itwascontrolledbythefewinstructions.Itwasthefirstautomatedmechanicalmachineandstillsameprincipleisbeingused.SoheisconsideredastheFatherofComputer.

Lady AdaAugusta
AdawasthestudentofCharlesBaggage.ShesuggestedBabbagetouseBinarynumbersystem.Shealsodevelopedasmallprogramfortheanalyticalengine.So,shewasconsideredasthefirstprogrammer.ShewashonoredbygivingtheprogramminglanguagenameAdaProgbyUSDepartmentofDefense.
Gorge Boole
GorgeBooledevelopedtheMathematicalLogicintheearly1850scalledBooleanAlgebra.ItistheprincipleDigitalElectronics.

HermanHollerith
AnAmericanStatistician,developedthefirsttabulatingmachine.Itusedpunchedcards.HestaredcompanycalledTabulatingMachineCompany(TMC).Aftermergingfewothercompanies,heestablishedInternationalBusinessMachine(IBM)Companyin1923.IBMistheworld’slargestcomputermanufacturingcompanytilldate.
JohanVonNeumann
Inlate1940s,AmericanScientistJohnVonNeumanndevelopedthestoredprogramconceptinwhichtheprogramcouldbestoredinamemoryandthecomputerwasexecutedytheprogram.HealsosuggestedthemodernarchitectureforComputerSystem

Age of Electromechanical Computers

MarkI(ASCC)
ThefirstelectromechanicalcomputerMarkIwasdevelopedbyProf.HowardAikenin1937.ItwasalsocalledIBMAutomaticSequenceControlledCalculator(IBMASCC).Itwashugemachine(51X8X3)Feetdimensionswith750000parts.Itconsumedlotsofelectricityandused18000VacuumTubes(ThermionicValves).In1944,HemodifiedMarkIanddevelopedanothercomputercalledMarkIIwhichused19000VacuumTubes.
ABC(AtanasoffBerryComputer)
J.V.AtanasoffandhisstudentCliffordBerryinventedthecomputercalledABCin1942atIOWAStateUniversity.Itused18045valves,andsomecapacitorsforstorageofelectricalcharges.Itusedpunchedcardforsecondarystorage.

Age of Electronics Computer

ElectronicNumericalIntegrator&Calculator
ENIACwasthefirstgeneralpurposeelectroniccomputerdevelopedbyDrJ.W.MauchlyandJ.P.Eckertin1946withthehelpofMooreSchoolofTheUniversityofPennsylvania.Itusedhighspeed18000vacuumtubes,70,000registersand10,000capacitors.Itcouldperform5000additionsand300multiplicationin1second.ItwasusedinUSArmForce.
ElectronicDelayStorageAutomaticComputer
EDSACwasdevelopedbytheProf.MauriceWilkesatCambridgeUniversityin1949byapplyingstoreprogramconceptofJ.V.Neumann.Itused3000vacuumtubesandmercurydelaylinesasmemory.Programmingwascarriedoutbyusingpapertapeandresultswereprintedonpaperbytele-printer.

ElectronicDiscreteVariableAutomaticComputer
EDVACwasinventedbytheJ.W.MauchlyandJ.P.Eckert.AlthoughitwasstaredbeforeEDSAC,itwascompletedin1952,soitwasconsidredasthefirststoredprogramconceptofJohnVonNeumann.Itwasthefirstbinarynumbersystembasedcomputer.
UniversalAutomaticComputer
In1961,J.P.EckertandJ.W.MauchlydevelopUNIVAC.Itwasthefirstgeneralpurposeelectronicdigitalcomputermadeforcommercialandadministrativeuse.

SteveJobs
StevenPaul"SteveJobs”wasfamouscomputerscientists,founder,andco-founderofmanycompanieslikePixarAnimationStudios(WaltDisneyCompany),NeXTInc.andAppleInc.(1978).HedevelopedfirstGraphicalUserInterfaceforAppleLizainearly1980.Here-joinedAppleCompanyin1996asaCEO.Hismaincontributionsare:MacOS,iworks,ipod,iphone,itune,etc.AfterresigningasCEO,fewmonthlaterdiedinOctober2011.
BillGates
WilliamHenryBillGatesIII“BillGates”istheprogrammer,founderandCEOoftheworld’slargestcomputersoftwarecompanyMicrosoft.HeandhisfriendPaulAllenestablishedMicrosoftin1975.Heisthemostwealthiestpersonoftheworldduring1995to2009andevenintheyear2013.HismaincontributionsareWindows,OfficePackages,SQLServer,etc

Generations of Computer

GenerationsofComputerdefinethestepwisedevelopmentofthecomputersystemsine1940stilltoday.
Eachgenerationistentativelydividedinto10yearstimeperiod.
Thecost,size,speed,powerconsumptionandtechnologiesusedindifferentgenerationsarediscussedinthegenerationsofcomputer

First Generation of Computers (1940-1955)
Largesizecomputerswhichusedvacuumtubes,mercurydelayasmemory,punchedcardsasstoragewithmachinelevelinstructionswerecalledfirstgenerationcomputer.
Vacuumtubesaretheelectronicvalvesthatcontrolsflowofelectronswiththehelpofelectricandmagneticfields.
ItwasfirstdevelopedbyLeeDeForestin1908.
Theyproducedheatduethethousandsofvacuumtubesusedinit,soitrequiredair-condition.
Theyconsumedlargeamountofelectricity.

Theywareveryslowercomputerandthespeedwasmeasuredintermsofmillisecond.
Theywereveryexpensiveandnotforthecommercialpurpose.
Machinelevellanguageandassemblylanguageswareused:
PunchedcardsandMercuryDelaywereusedasmemoryunit
NoproperInput/OutputDeviceswereusedandalmostallcomponentsweremanuallyassembled.
Examples:MarkI,ENIAC,EDSAC,EDVAC,UNIVAC,IBM700series,etc.

Second Generation of Computers (1956-1963)
Computerswhichusedtransistorsasprocessingelementwerecalledsecondgenerationcomputer.
Atransistorissemiconductorelectronicdevicethatamplifythesinglesoropenandcloseacircuit.
Transistorswereinventedbythreescientists:WilliamShockley,JohnBardeenandWalterBratainin1947.
1000sofvacuumtubeswerereplacedbyonetransistor.
Itconsumedverylowamountofelectricityanddidnotproducelargeamountofheatascomparetovacuumtube.
Computersweremorefasterthanfirstgenerationandthespeedwasmeasuredintermsofmicrosecond.

Magneticcorememorieswereusedasprimarymemoryandmagneticdrumandtapewereusedassecondarymemory
IthadfasterandmoreefficientI/Odeviceslikekeyboardandmonitor
AssemblylanguagesandHighlevellanguagessuchasCOBOL,FORTRANwereused.
Theywerestillmoreexpansive,neededfrequentmaintenanceandmanualassemblyofpartsweretobedone.
Examples:IBM1401,PDP-8IBM7090,etc.

Third Generation of Computers (1964-1970)
ComputerswhichusedIntegratedCircuits(IC)arecalledthirdgenerationcomputers.
ICisthemicroelectronicssiliconchipthatcontainsthelargeamountofdigitalelectroniccomponentssuchastransistors,registers,logicalgates,etc.
Thousandsoftransistorsarereplacedbyasmallchip.
ItwasfirstdevelopedbyJohnKilbyandRobertNoycein1958
Computersbecamemoresmaller,moreefficient,morefasterandspeedwasmeasuredinnanosecondsandlesser.
Theyconsumedlesselectricityandproducedverylessheat
Computerwaremostlyusedinbusiness,generalpurposeandevenpersonalpurposes.

AdvancedI/OdeviceslikekeyboardCRTmonitorandmousewereused.
HighlevellanguagessuchasBASIC,C,PASCALwereused
OperatingsystemswithCUIinterfacewereused.Examples:Unix,Xenix,etc
Semiconductormemories:RAMandROMwereusedasprimarymemoryandmagneticdrum,tapewerewidelyusedassecondarymemory.
Stillveryexpansive,beyondthecapacityofpoorpeople.
Examples:IBM360Series,IBM
UNIVAC9400andNCR395,etc.

Fourth Generation of Computers (1971-Till)
ComputerswhichusedVeryLargeScaleIntegratedCircuits(VLSI:Microprocessor)arecalledfourthgenerationofcomputers.
Microprocessorisasquaresiliconchipinwhichmillionsofmicroelectronicscomponentsareintegratedtogether.
FirstcommercialmicroprocessorIntel4004wasmadebyIntelcorporation.
Itismorereliable,fasterandconsumedverylittleamountofelectricity.
SpeedismeasuredinpicosecondsorMIPS(MillionsInstructionsPerSecond)
Semiconductormemories,magneticmemories,opticalmemories,flashmemories,cachememory,etcarewidelyused.
UserfriendlyInput/OutputDeviceswithGUIInterfaceareused.

MultiprocessingOperatingSystemwithtouchsensitiveuserinterfaceareused.Example:MSWindows,Linux,Solaris,MacOS,Android,etc
Advancedprogramminglanguages:Visual.net,Java,Python,Oracle,SQLServerandSmartapplicationsstore:itunesandplaystoreareused.
Hardwarelike:wirelessperipherals(WiFi),2D,3DSoundCard,GraphicsCards,BiometricDevices,etc.areintroduced.
Computersarenotonlyusedfordataprocessingbutalsousedforcommunications.
Highspeednetwork,Internet,Multimedia,Animation,etcareintroduced.
Examples:IBM-PC,HP,Compaq,Acer,AppleMac,MacBook,Notebooks,TabletPC,etc

Fifth Generation of Computers (Future)
ThefastestfuturegenerationcomputersbasedonArtificialIntelligence(AI)arecalledfifthgenerationcomputers.
AIisthebranchofcomputerscienceconcernedwithmakingcomputersbehavelikehumans.
Thesecomputersarenotcompletelydevelopedanddifferentresearchesaregoingonthedevelopmentofsuchcomputers.
Computercouldbemoreintelligentandknowledgebasedwhichwouldhavecapacitytothinkandtomakelogicaldecisionslikehumanbeing.
Bio-chemicalsuperconductormaterialsGalliumArsenideorProteinFiberswouldbeusedtoincreasetheprocessinganddecisionmakingcapacity.

NaturallanguagescouldbeusedasinstructionstothecomputerlikeEnglish,Nepali,Hindi,German,etc.
AIandNaturallanguageswouldmakecomputermoreuserfriendly.
AdvancedprogramminglanguagesareusedlikeProlog,LISP,etc.
ManyProjectareworkinginthefield:
DARPAProject(DefenseAdvancedResearchProjectAgency)inUS
MEC(MicroelectronicComputertechnology)inUS
Japanalsoactivelyinvolvedinthisfield.
Majorachievementsfromtheresearchesoffifthgenerationcomputersare:
Patternrecognitions
NaturallangrageProcessing
ExpertSystem
Robotics

Scale of Integration
IntegratedCircuitsareclassifiedinthedifferentcategoriesonthebasisofscaleofintegration.Itdefinesthenumberofmicroelectronicscomponentssuchastransistorsinachip.
SSI(SmallScaleIntegration)
Chipcontentsabout10transistors
MSI(MediumScaleintegration)
Chipcontentsabout100transistors
LSI(LargeScaleintegration)
Chipcontentsabout10000transistors
VLSI(VeryLargeScaleintegration)
Chipcontentsabout100000transistors
ULSI(UltraLargeScaleIntegration)
Chipcontentsabout1000000transistors

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